Hi Jan,

The book to get is Real World Camera RAW with CS4 by Fraser and Schewe. although you're using Lightroom and not CS4, they share the same RAW conversion engine.

Jeff Schewe (and the late Bruce Fraser) are (Jeff) / was (Bruce) Adobe "insiders", and played a significant part in the development of the product - so it's very authoritive.

PS: Looks like you've got some quite large dust spots on your sensor - might be time for a clean!